The Oscar winner attended the movie event earlier this week (begs13Sep10) to publicise the emotional drama, which she starred in and produced.
The actress admitted she found her double role terrifying - and revealed to reporters that she was perspiring with fright.
She told reporters, ""The reason I'm wearing this jacket is because I'm sweating under here and I can't take it off 'cause this shirt shows it.
""I feel very exposed, very nervous. It's a whole different ball game because... I'm responsible for this film, so it's a big weight. But I'm glad that we made it.""